FORTE Bill Horvitz's large ensemble includes his brother, Wayne Horvitz.

When Forestville guitarist Bill Horvitz decided to compose an ode to his deceased brother, the result was The Long Walk, an album that pairs bright, big-band jazz and playful improvisation with somber cello strains in a complex meditation on loss to be performed this weekend.

Nowhere is the tension between past memories and present grief more evident than the album's sixth track, "Child Star." Horvitz recalls that as young as age four, his younger brother Phillip used to choreograph Broadway-themed dances, working on them for months, memorizing them and then making tickets and programs for his family members. The eight-minute piece builds on a flurry of bright drum and brass lines that, at one point, give way to a rat-tat-tat reminiscent of a marching band.

Toward the end of the track, the mood completely changes, with a quiet, echoing guitar line played against a sparse backdrop of piano and cello. "To me, that's kind of an acknowledgment of what happened," Horvitz says.

What happened is that Philip boarded a plane in 2006, at the age of 44. He died of heart failure during the flight.

"He fell asleep and never woke up," Horvitz says.

After this shocking event, the guitarist says he immediately knew he wanted to memorialize his brother, who had become a writer, dancer and choreographer in New York. For a year, he didn't know exactly how. Finally, while developing an old roll of film, he found a picture of Phillip with a sock monkey on his shoulder.

"This song 'Where Did the Monkey Go?' just came to me, and after that I started working on the album," he says.

The brass, drums and strings whirl in controlled spiral on that piece, the album's fifth track, giving way to series of solos. This is reflective of The Long Walk as a whole, which Horvitz planned as a combination of tightly arranged musical sections and open-ended improvisation, overseen by conductor Omid Zoufonoun.

"Almost everyone improvises," Horvitz says of the collection of 17 veteran players known as the Bill Horvitz Expanded Band. Though most of the ensemble members are from the Bay Area, the group also features Horvitz's other brother, Wayne, a pianist famed for his work in traditional jazz circles, as well as John Zorn's experimental group Naked City.

While the album draws largely on the local Horvitz's dual background in jazz and folk—past collaborations have included Zorn, Elliott Sharp and George Cartwright—there are places where memories of his brother sparked arrangements that Horvitz hadn't set out to create.

"Things would appear that didn't seem to be so much me, as him," he says. "I can't really explain it, but I worked with those. I left them in."